A new intermediate in the biosynthesis of peptidoglycan has been detected. Experiments will be undertaken to determine how the pool size of this intermediate changes in response to treatment of B. megaterium with antibiotics that perturb peptidoglycan synthesis. Antibody has been prepared that is directed against the teichuronic acid of B. megaterium. This material should serve as a selective agent for teichuronic acid-less mutants. Such mutants should help in understanding the physiological role of teichuronic acid.